Hundreds of containers have been removed from the Rena eight months after the ship grounded off the Tauranga coast - completing the first stage of the salvage operation.

Rena crashed into the Astrolabe Reef ealy on October 5. The cargo ship's captain Mauro Balomaga, 44, and navigator Leonil Relon, 37, both faced charges under the Maritime Transport Act for operating a vessel in a manner likely to cause danger, under the Resource Management Act for discharging a contaminant and three charges under the Crimes Act for altering ship documents.

Balomaga also faced an additional charge of altering ship documents. They pleaded guilty to all charges and were last month jailed for seven months.

Since the grounding, a total of 940 accessible containers have been moved ashore. But more work needs to be done, with attention now shifting towards removing the wreck from the water, Maritime New Zealand (MNZ) said today.

While salvage company Svitzer have packed their bags, the owners and insurers of the Rena have issued a tender for the work.

Container recovery company Braemar Howells/Unimar would monitor the wreck site until the tender was awarded.

"We've established an exclusion safety zone which is being patrolled 24-7, and so far there have been no incidents or releases," operations manager Neil Lloyd said.

"We can assure Bay of Plenty people that the wreck is not being left on its own unattended, as some media have incorrectly reported.

"We are extremely well placed to respond to any releases with a variety of tugs, barges and fast response craft, and well-tested response plans."

Lloyd said low swell conditions allowed the Unimar team to lift five of containers from the seabed this week.

"While the fine weather this week meant we could push ahead, a huge amount of work has gone into this new phase in the recovery work, including safety preparations, and weight calculations," Lloyd said.

"A specialised dive team using a vessel equipped with a decompression chamber was used; divers were sent down to pre-rig containers and prepare them safe lifting."

Lloyd said the recovery team spent some months preparing - with sonar equipment and more recently a remote operated underwater vehicle - to fix the containers positions for recovery.

More containers in water less than 50 metres deep would be lifted off the seabed over coming weeks, when weather conditions allow it, he said.

Braemar response teams have recovered debris, including refrigeration foam, sawn timber, plywood sheets and plastic beads, from an area running from Pukehina to Matata and Waihi Beach.

Similar work was continuing on the Coromandel Peninsula where large amounts of small flotsam has been recovered from isolated coves. Areas including Sailors Grave and Hot Water Beach were still being impacted by plastic beads washing ashore.

Lloyd said the shoreline work was also continuing on Matakana Island, where some re-cleaning has been necessary. Operations were also planned for Motiti Island.